The present invention relates to a control technique of a magnetic disc storage apparatus and more specifically to a control technique of a voice coil motor for moving a magnetic head to read or write information from or to the storage track on a magnetic storage disc to be driven to rotate. A voice coil motor control technique has been disclosed in the patent application presented by the applicants of the present invention filed on Dec. 12, 2001 Ser. No. 10/012,401).
A magnetic disc storage apparatus comprises a magnetic head for reading or writing information from or to a storage track on a magnetic storage disc to be driven to rotate, a voice coil motor for moving this magnetic head on the magnetic disc and a voice coil motor drive controller for positioning the magnetic head by controlling a voice coil motor drive current while monitoring the read condition of the magnetic head.
Information storage density of a magnetic disc storage apparatus has been improved from year to year and thereby still higher accuracy has also been required for the positioning control of the magnetic head. Therefore, it has been proposed that the magnetic head is positioned through the feedback control of a drive current of the voice coil motor on the basis of a detected value of the relevant drive current. In order to drive the voice coil motor for moving the magnetic head, a linear drive system has been employed in which amount of a voice coil motor drive current is continuously changed.